The need for clean drinking water is universal. Worldwide, poor drinking water quality is estimated to kill up to 2.5 million people annually as a direct or indirect cause of diseases.
In developed countries, water supply systems typically include built-in water treatment plants, where water is purified from harmful impurities and chlorinated in order to kill viruses and bacteria. In larger systems, where the water is distributed over a large area at considerable distance from the treatment plants and relatively lengthy water pipes are required, the disinfection process is often augmented by adding excessive amounts of chlorine to the water. Such chlorination significantly reduces the exposure to the spread of infectious diseases through the water system. However, the presence of chlorine imparts objectionable odor to water, and some chlororganic compounds are themselves detrimental to health. Therefore, even centralized tap water purification does not guarantee quality, both in terms of healthiness and consumer experience. Furthermore, even in such large water supply systems, the water is typically exposed to contamination from various harmful elements such as iron, heavy metals and their oxides, rust, pesticides, lime, etc.
One of the simplest and most widespread methods of additional water purification in domestic conditions is by filtration in “filter-pitchers”. Such filter-pitchers typically provide “esthetic treatment” that improves the smell and/or taste of the water by dechlorinization, the removal of particles in the water and scale treatment with ion exchange resin. The most popular filter-pitchers are those produced by Brita, Culligan, Kenwood, and General Electric (GE). The construction of these devices tends to be very simple and typically constitutes a container separated by a partition into upper and lower parts. A cartridge-type filter is arranged in the partition. The upper part of the container is filled with water that passes through the filter into the lower part.
Present-day filters are typically multilayer; they provide increased filtration efficiency with multiple sorbent layers containing, for example, activated carbon powder and ion-exchange resin layers. The filter pores are sufficiently large to ensure a satisfactory output of around 3-5 liters of water per hour. Such filters reduce unpleasant phenomena such as chlorine odor, turbidity and yellowish color of water, metal-like flavor and/or oily surface film. Good filters also decrease water hardness to an acceptable level. During the course of normal operation, contaminating materials tend to build up in the filter; accordingly, the filters should be replaced approximately once a month. Manufacturers also typically recommend cleaning the internal walls of the pitcher during the filter replacement, i.e. once a month.
Other methods for water purification in a water pitcher are also known in the art. For example, UV light sources can be used inside a pitcher for water disinfection. PCT publication WO2007078294 discloses such a method. Ozone treatment may also be used, as disclosed in U.S. Pat. Nos. 5,900,143, 6,110,431, 6,200,473, 6,673,248, and 7,135,106.